RE: the best caliber
The only one on your list that should be used past 300yds is the 25-06. Based on your criteria I dont think you understand long range shooting enough to try it on animals. targets, knock yourself out, but you owe it to the animals to use the right tool on them. You eliminated all the long action rifles, long shots are EXACTLY what they are made for, otherwise we'd all be useing short actions out west , which is the exception not the rule(the short mags are the exception). I'd say get a 25-06,270,264win,280,7mag,30-06,300 mag.